2002 XG-350 enging surging problem- high standing idle

Hi to all - I have a 2002 XG350 that I purchased new. It now has
about 131K on it and has been a relatively trouble free car to this
point. A couple of months ago I noticed that the idle was quite high
while the car was stommed and in gear. It could probably get to 20
mph without using the accellerator pedal.

I brought the car to the dealer and was told that since there was no
code/check engine light, that they couldn't diagnose the problem. I
few weeks later there was a check enging light so I brought the car
back in. They told me that it needed new ignitiuon coils, and a
sensor that controlled the coils. While the car was in I got a call
and was told that they also replaced the throttle position sensor.
The car runs somewhat better but the problem of the high standing idle
is still there, $600. later. Apparently the techs don't know how to
adjust the idle.

I'm wondering if anyone has had a similar experience with a huyndai
and maybe a solution.

Many thanks, Vic

 

Thats odd. I,ve got a 2002 V6 Sonata that has a high idle. Thinks its the
same engine bored/stroked out a bit for the XG350. Likewise the dealers
seemed incapable of adjusting idling speed. If it was idling that high and
smoothly I,d seriously doubt the coil pack was faulty. I,ve had them fail
and totally the opposite.
John

 

The idle (and in this case, throttle) are computer controlled. No
check engine lamp isn't the same as can't be diagnosed. No check
engine lamp simply means that the computer's self-diagnostic
capabilities haven't determined there's an actual problem.

There are several items for the technician to investigate:
- Is the idle high due to computer request? If so, the various inputs
to the ECM and throttle module (ETM) should be checked for proper
values. Accelerator and throttle position sensors are strong
potential candidates for this type of issue.
- Is there an air leak bypassing the throttle plate? This would cause
a high idle.
- There could be a fault in the throttle body or the ETM, but both of
these will typically set a trouble code pointing the technician in the
correct direction.

Do you know what trouble codes were retrieved? Any chance the plugs
were recently replaced or the intake plenum was pulled for some other
reason?